The police were called to Count Gottfried von Bismarck's penthouse flat in Draycott Place in Chelsea at exactly 5.39am on Friday morning. It takes a certain fatal and Bacchanalian talent for decadence, excess and self-destruction to achieve the dubious distinction of troubling the police at dawn not once but twice within 20 years of your party devoted life.

Call it Bismarck Revisited. Whatever the result of police enquiries into the mysterious death of 38-year-old Anthony Casey, it was inevitable that photos of the German count fully made up in riotous and lipsticked exotic-pompadour-boy Oxford party mode (fishnet stockings were often part of his undergraduate uniform) from the Eighties would be splashed over the papers both in both Britain and Germany. And that there would be an unhappy dredging up of the facts surrounding the 1986 death of heiress Olivia Channon, daughter of Tory minister Paul Channon, killed by a drug overdose in von Bismarck's rooms at Christ Church.

Friends of von Bismarck still insist that Gottfried had nothing to do with Olivia Channon's death, nor did he supply her with heroin and that she merely passed out in his rooms, but his grand aristocratic Bismarck name has been tarnished ever since.

He dropped out of the Euro-society spotlight for a decade or so, helping East German firms in the transition to privatisation and pursuing a career as an occasional actor (playing himself) in various obscure movies, then getting mixed up in a failed telecom company owned by Kevin Maxwell. But Gottfried, whom I have known for years, has never lost his appetite for serious nocturnal enjoyment. He is an affable, amusing, sartorially elegant man and, in the louche stakes, is out on his own.

Von Bismarck is the type of German aristocrat who - had he lived in the late 19th century - would have been perfectly happy living out a decadent and sybaritic life of hedonism in a villa nestled away on Capri, which, in the 19th century and up until the Second World War, was the favoured play resort for gay aesthetes. Gottfried would certainly also have been at home in Berlin and Hamburg in the Thirties.

Although his name gives him a certain notoriety and fame in Britain, he is far from alone in being representative of a certain class of very troubled German aristocrat whose DNA is simply not suited for the modern, politically correct world of Tony Blair and German chancellor Angela Merkel.

London has become the official Happy Valley of the socially displaced, aristo Euro-royal set. Although the von Bismarck name is one of the most famous in Germany (on a level with English royalty) it is entirely understandable that Gottfried - and other members of the large Bismarck clan - choose to live in London, which is where today's enfants terribles of the Euro-society gravitate, just as the party-loving members of English, French, German society gravitated to Kenya and the Muthaiga Club in the Twenties and Thirties. They usually head to Chelsea and the bar at Blake's, next door to von Bismarck's flat.

As one royal prince explained to me, much of the attraction of living in London is that it has such limited social appeal to the older generation of Euro-aristocrats.

Another German aristocrat who came to London, only to cast something of a shadow over the great family name, is Prince Ernst of Hanover, now married to Princess Caroline of Monaco. Although he no longer lives in the city, Ernst, like Gottfried, has been turned into a notorious figure by the tabloid press in Europe, on account of a series of loutish incidents, often fuelled by alcohol, and his royal connections: Ernst is a cousin of the Queen.

Quite what personal demons led Gottfried to live such a different and alternative lifestyle from his older brother Gregor - a married film producer who lives in London - nobody really knows. His professional career, since leaving Oxford, is certainly not what he is well known for.

A friend who had dinner with him a year ago in London said: 'He was looking a bit strange. Pale, thin and sweating a lot but was full, as ever, of brilliant and obscure conversation. He knows an awful lot about 19th and 20th century German and English history - much more than most English - but he definitely came across as a darkly complex man.'